1. Field of the Invention
The present invention relates to an inspection unit having a radiation tunnel with at least one entrance being shielded outwardly by a radiation shielding apparatus.
2. Description of the Background Art
Conventional inspection units have, particularly at an entrance of a radiation tunnel, a radiation-shielding curtain so that when a luggage piece or other object to be inspected is fed into the inspection unit no ionized radiation can exit at this area. A radiation-shielding curtain is respectively mounted therefor at at least a front area of the radiation tunnel of the inspection unit, and also often at a rear area thereof if an exit of the tunnel is open when the object is ejected. Such a radiation-shielding curtain is normally made of a plurality of downwardly-hanging, thick, lead cloths, which are mounted directly adjacent to one another in a row.
Because of the introduction of new x-ray protection regulations and a reduction in radiation threshold values associated therewith, additional shielding measures are necessary in such inspection units. Previously-used lead cloths and curtains of lead-containing material even today often quite substantially impair the flow of luggage pieces by the onset of friction, which depends upon the weight of these curtains. Additional shielding for achieving smaller threshold values mean an increase of this weight because of an increased lead content in the shielding material. A greater weight of the curtain causes, however, a higher resistant force of the curtain that negatively affects the luggage pieces.
It is therefore an object of the present invention to provide a radiation shielding apparatus in a zone of a radiation tunnel of an inspection unit that meets the new tightened threshold values and, nevertheless, assures an unimpaired transport through the inspection unit.
According to principles of the invention, instead of arranging a single curtain of flexible lead cloths with great weight that cause a significant hindrance of the flow of luggage pieces, a plurality of light curtains are arranged at a particular spacing behind one another, so that the friction force is smaller than when a heavier curtain is employed.
By employing double-staggered curtains no increased resistance force is caused if the spacing of the light-in-weight curtains is approximately the length of the front-most curtain. A minimal spacing of the curtains should, however, not be less than half the length of the front, up-stream, curtain.
In further embodiments of the present invention, it is beneficial for the curtains to be coated with an additional material having a particularly small friction value.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.